Shutter for camera

Abstract

A shutter for a camera has a sector driven by a movable board having plural spiral-shaped coil patterns concentrically arranged thereon for generating a repulsive or attractive magnetic field with respect to fixed permanent magnets or coils confronting the movable board. A desired generated magnetic force can be obtained by setting the number and winding direction of the coils and combining coils in a desired manner. A drive circuit is connected to the coils for controlling the supply of electricity thereto such that repulsive magnetic forces are generated while opening the shutter and attractive magnetic forces are generated while closing the shutter.

What is claimed is:  
     
       1. A shutter for a camera comprising: 
       a supporting plate having an opening therethrough;  
       a fixed printed board held by the supporting plate and provided with an opening therethrough, and having a plurality of coil patterns disposed thereon substantially in a concentric shape relative to a center of an optical axis of the opening, each coil pattern having a spiral shape;  
       a shutter base plate having an opening therethrough;  
       a movable printed board having one face confronting one face of the fixed printed board and being pivotably supported by the shutter base plate and having an opening therethrough, and a plurality of coil patterns disposed thereon substantially in a concentric shape relative to a center of an optical axis of the opening, each coil pattern having a spiral shape;  
       a biasing member for biasing the movable printed board in one direction; and  
       a plurality of sectors engaged to undergo pivotal movement with the movable printed board so as to open and close in response to pivoting of the movable printed board; and  
       a drive circuit connected to the coil patterns for controlling the supply of electricity to the coil patterns such that repulsive magnetic forces are generated while opening the shutter and attractive magnetic forces are generated while closing the shutter.  
     
     
       2. A shutter for a camera according to  claim 1 ; wherein the fixed printed board and the movable printed board have through holes therein, respective coil patterns are arranged on confronting faces of the respective printed boards, and connecting portions for connecting terminals with the coil patterns and for connecting the respective coil patterns are provided on faces of the printed boards which are not confronting each other and are connected to the coils via the through holes. 
     
     
       3. A shutter for a camera according to any one of claims  1  or  2 ; wherein the respective coil patterns are equally spaced about confronting faces of the respective printed boards and, in an initial state, positions of the respective coil patterns of the movable printed board are deviated from positions of the respective coil patterns of the fixed printed board in an advancing direction by a predetermined angle. 
     
     
       4. A shutter for a camera according to any one of claims  1  or  2 ; wherein the respective printed boards comprise multilayer printed boards each having at least two or more faces, and coil patterns wound in the same direction are arranged on at least two or more faces. 
     
     
       5. A shutter for a camera according to any one of claims  1  or  2 ; wherein contiguous ones of the coil patterns on the respective printed boards are wound in opposite directions. 
     
     
       6. A shutter for a camera, comprising: 
       a supporting plate having an opening therethrough;  
       a plurality of permanent magnets arranged on the supporting plate;  
       a shutter base plate having an opening therethrough;  
       a movable printed board having one face confronting the permanent magnets pivotably supported by the shutter base and having an opening therethrough, and having a plurality of coil patterns disposed thereon substantially in a concentric shape relative to a center of an optical axis of the opening, each coil pattern having a spiral shape;  
       a biasing member for biasing the movable printed board in one direction;  
       a plurality of sectors engaged to undergo pivotal movement with the movable printed board so as to open and close in response to pivoting of the movable printed board; and  
       a drive circuit connected to the coil patterns for controlling the supply of electricity to the coil patterns such that magnetic forces between the coil patterns and the permanent magnets repel each other while opening the shutter and attract each other while closing the shutter.  
     
     
       7. A shutter for a camera according to  claim 6 ; wherein the permanent magnets are alternately arranged with N poles and S poles and contiguous coil patterns of the movable printed board are wound in opposite directions. 
     
     
       8. A shutter for a camera according to any one of claims  6  or  7 ; wherein the coil patterns are arranged on opposite faces of the movable printed board. 
     
     
       9. A shutter for a camera according to any one of claims  1  or  6 ; wherein the drive circuit controls the supply of electricity to the coil patterns in accordance with a brightness of an object to be photographed. 
     
     
       10. A shutter for a camera according to  claim 1 ; wherein the biasing member biases the movable printed board so that the coil patterns disposed thereon are deviated from the coil patterns disposed on the fixed printed board at an initial position by a predetermined angle by a biasing force of the biasing member. 
     
     
       11. A shutter for a camera according to  claim 1 ; wherein each of the printed boards comprises a multilayer printed circuit board having at least two or more faces, the respective coil patterns are arranged on opposite faces of the respective printed boards, and the respective coil patterns formed on the respective faces of the printed boards are wound in the same direction and connected to each other. 
     
     
       12. A shutter for a camera according to  claim 1 ; wherein the fixed printed board comprises a disk-shaped printed circuit board having the coil patterns printed thereon and the opening formed therein is in alignment with the openings formed in the supporting plate, the shutter base plate and the movable printed board. 
     
     
       13. A shutter for a camera according to  claim 12 ; wherein the movable printed board comprises a disk-shaped printed circuit board having the coil patterns printed thereon and the opening formed therein is in alignment with the openings formed in the supporting plate, the fixed printed board and the shutter base plate. 
     
     
       14. A shutter for a camera according to  claim 1 ; wherein the openings formed in the supporting plate, the shutter base plate, the fixed printed board and the movable printed board are in alignment. 
     
     
       15. A shutter for a camera, comprising: a base plate; a movable plate pivotably supported by the base plate and having magnetic field generating elements disposed on at least one surface thereof; one or more sector members engaged to the movable plate to undergo pivotal movement therewith to open and close a shutter aperture of the camera; a fixed plate confronting the movable plate and having one or more magnetic field generating elements disposed on at least one surface thereof confronting the magnetic field generating elements disposed on the movable plate, the magnetic field generating elements formed on at least one of the movable plate and the fixed plate comprising a plurality of coil patterns for generating a magnetic field in response to a current passing therethrough, the coil patterns being wound in the shape of spirals and being connected to each other such that an inner turn of one spiral is connected to an outer turn of an adjacent spiral; and a drive circuit for selectively supplying a current to the electromagnets to produce a repulsive magnetic field to cause the movable plate to pivot with respect to the fixed plate to open the aperture defined by the sector members and to produce an attractive magnetic field to cause the movable plate to pivot with respect to the fixed plate to close the shutter aperture defined by the sector members. 
     
     
       16. A shutter for a camera according to  claim 15 ; wherein the coil patterns are all wound in the same direction, and the drive circuit supplies current to the coil patterns in a first direction to produce a repulsive magnetic field between the fixed plate and the movable plate to open the sector members when opening the shutter and supplies current to the coil patterns in a second direction to produce an attractive magnetic field between the fixed plate and the movable plate to close the sector members when closing the shutter. 
     
     
       17. A shutter for a camera according to  claim 15 ; wherein the movable plate comprises a disk-shaped printed circuit board having an opening in a center thereof in alignment with the shutter aperture of the camera, and having a plurality of coil patterns printed thereon in a concentric arrangement relative to the opening formed therein. 
     
     
       18. A shutter for a camera according to  claim 17 ; wherein the fixed plate comprises a disk-shaped printed circuit board having an opening in a center thereof in alignment with the shutter aperture of the camera, and having a plurality of coil patterns printed thereon in a concentric arrangement relative to the opening formed therein. 
     
     
       19. A shutter for a camera according to  claim 15 ; wherein the magnetic field generating elements disposed on the fixed plate comprise a plurality of permanent magnets. 
     
     
       20. A shutter for a camera according to  claim 15 ; further comprising a biasing member for biasing the movable plate so that the coil patterns disposed thereon are deviated by a predetermined angle from the magnetic field generating elements disposed on the fixed plate.